1. Field of the Invention
The present invention relates to a user apparatus and a program, both for use in a content distribution/presenting system, for example to the invention relates to a user apparatus and a program, which are designed to prevent any content to be viewed, from being played back without playing back sub-content items such as commercials.
2. Description of the Related Art
In the field of content distribution, there has recently risen a new service of stream-distributing free content items, each headed with the sponsor's commercial.
For this content distribution service, it is important that users view the sponsors' commercials. In view of this, a method has been developed, in which a questionnaire is sent out right after a commercial video has been transmitted, asking the viewers if they have viewed the commercial, and the main-content item is then stream-distributed to the terminals of only those users who have answered in affirmative to the questionnaire.
Prior-art references that seem related to the present invention are, for example, Jpn. Pat. Appln. KOKAI Publication No. 2003-273819 and A. Shamir, “How to share a secret,” Communications of the ACM, 22, 11, pp. 612-613 (1979).
The above-mentioned method, in which the questionnaire is sent out, is disadvantageous, however. Once the main-content item has been saved in a local environment, such as the user terminal, the user can view the main-content item, without the necessity of viewing the commercial provided at the head of the content.